Magnetoresistance effect device and magnetoresistance effect head comprising the same, and magnetic recording/reproducing apparatus

ABSTRACT

In the present invention, a thin film whose main component is a metal having a specific resistance of 4 μΩ·cm to 200 μΩ·cm is used as a nonmagnetic layer of a so-called CPP-GMR element. Therefore, even when an area of the element becomes limited, the element is not increased excessively in resistance. Thus, even when a magnetic gap is narrow, a large output can be obtained.

This application is a 371 of PCT/JP01/05334 filed Jun. 21, 2001.

TECHNICAL FIELD

The present invention relates to a magnetoresistive element, amagnetoresistive head and a magnetic recording and reproducing devicesuch as a hard disk device using the magnetoresistive element.

BACKGROUND ART

In recent years, hard disk drives have had considerably increasedmagnetic recording density. In such a trend, significant advances alsohave been made in reproduction magnetic head technology. Particularly,the use of a spin valve type magnetoresistive element (MR element)utilizing a giant magnetoresistive effect (GMR) allows the sensitivityof a magnetoresistive head (MR head) to be improved substantially.

The spin valve type MR element includes two ferromagnetic layers and anonmagnetic layer interposed between the two magnetic layers. Themagnetization direction of one of the ferromagnetic layers (pinnedlayer) is fixed by an exchange bias magnetic field generated from amagnetization rotation suppressing layer (pinning layer; thisferromagnetic layer and the magnetization rotation suppressing layer arereferred to collectively as an exchange coupling film). Themagnetization direction of the other ferromagnetic layer (free layer)changes according to an external magnetic field. As a result, a relativeangle formed by the respective magnetization directions of the pinnedlayer and the free layer changes, and this change in relative angle isdetected as a change in electric resistance.

The spin valve type MR element has, for example, a known configurationin which a Ni—Fe film, a Cu film and a Fe—Mn film are used as a magneticlayer, the nonmagnetic layer and the magnetization rotation suppressinglayer, respectively. When these materials are used, a magnetoresistancechange ratio (MR ratio) of about 2% is obtained (Journal of Magnetismand Magnetic Materials 93, p. 101, 1991). Since the use of FeMn as amaterial for the magnetization rotation suppressing layer results in asmall MR ratio, and the corrosion resistance provided by FeMn itself isnot sufficiently high, PtMn- and NiMn-based materials have been used forreproduction magnetic heads for hard disks. Further, it has beenreported that an element in which an oxide such as NiO, α-Fe₂O₃ or thelike is used for a magnetization rotation suppressing layer provides anMR ratio of 15% or higher.

Considering that further increases in magnetic recording density will beachieved, it is expected that existing GMR elements will reach theirlimits and result in shortage of output. With this in view, vigorousstudies have been made on TMR (Tunnel Magnetoresistance) elements.Compared with the GMR elements, the TMR elements provide larger amountsof change in resistance, and the resistance itself of the TMR elementsis considerably higher. In a TMR element, an insulation film of Al₂O₃ orthe like is used as a nonmagnetic layer, and sensing is performed usinga tunnel current passed in a direction perpendicular to a film plane.

However, the TMR elements have presented the following problem. That is,when an area of an element becomes extremely limited as magneticrecording density is increased, the resistance of the element becomestoo high.

DISCLOSURE OF THE INVENTION

With the foregoing in mind, it is proposed by the present invention thata so-called CPP-GMR (Current Perpendicular to the Plane) element is usedfor adaptation to further the achievement of super high-density magneticrecording. In the CPP-GMR element, current is passed in a directionperpendicular to a film plane while in a conventional GMR element,current is passed in a film plane (CIP, Current in Plane).

That is, a magnetoresistive element according to the present inventionincludes a first magnetic layer (free layer), a nonmagnetic layer, asecond magnetic layer (pinned layer) laminated to the first magneticlayer through the nonmagnetic layer, and a magnetization rotationsuppressing layer for suppressing magnetization rotation of the secondmagnetic layer. In the magnetoresistive element, the magnetization ofthe first magnetic layer is rotated more easily by an external magneticfield than the magnetization of the second magnetic layer, and a currentused for sensing is passed in a direction perpendicular to a film plane.The nonmagnetic layer is formed of a thin film whose main component is ametal having a specific resistance of 4 μΩ·cm to 200 μΩ·cm.

According to the MR element of the present invention, even when an areaof the element becomes limited, the element is not excessively increasedin resistance. Thus, even when a magnetic gap is narrow, a large outputcan be obtained.

In this description, “main component” refers to a component contained inan amount of not less than 80 atom %. Preferably, the metal having aspecific resistance falling in the above range constitutes not less than95 atom % of the nonmagnetic layer.

The present invention also provides an MR head including theabove-mentioned MR element and a magnetic shield. The magnetic shield isprovided for shielding the external magnetic filed that flows from otherthan a magnetic recording medium to the MR element. Furthermore, thepresent invention also provides a magnetic recording and reproducingdevice that includes the above-mentioned MR head and a magneticrecording medium used for performing information recording orreproduction using the MR head.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of a magnetoresistive element accordingto an embodiment of the present invention.

FIG. 2 is a cross sectional view of a magnetoresistive element accordingto another embodiment of the present invention.

FIG. 3 is a graph showing an example of how an exchange interactionbetween magnetic layers is changed with increasing film thickness of anonmagnetic layer.

FIG. 4 is a perspective view of a magnetoresistive head according to anembodiment of the present invention.

FIG. 5 is a perspective view of a magnetoresistive head using aconventional MR element.

FIG. 6 is a plan view of a magnetic information recording andreproducing device according an embodiment of the present invention.

FIG. 7 is a cross sectional view of a magnetic information recording andreproducing device according to an embodiment of the present invention.

FIG. 8 is a cross sectional view of an element fabricated in Example 1.

FIG. 9 is a cross sectional view of an element fabricated in Example 2.

EMBODIMENTS OF THE INVENTION

As shown in FIG. 1, an MR element according to an embodiment of thepresent invention has a multi-layered film in which a lower electrode 5,a magnetization rotation suppressing layer 4, a pinned layer 3, anonmagnetic layer 2, a free layer 1, and an upper electrode 6 arelaminated in order. In this element, the magnetization of the pinnedlayer 3 is pinned down by an exchange bias magnetic field generated fromthe magnetization rotation suppressing layer 4. The free layer 1 as theother ferromagnetic body is separated magnetically from the pinned layer3 by the nonmagnetic layer 2. Accordingly, the magnetization of the freelayer is rotated more easily by a magnetic field from the outside thanthe magnetization of the pinned layer.

Generally, when the magnetization directions of two magnetic layers areanti-parallel to each other, electrons are scattered at an interfacebetween the magnetic layer and a nonmagnetic layer, and thus an elementhas increased resistance. In contrast to this, when the magnetizationdirections are parallel to each other, electrons are hardly scattered atthe interface, and thus the element has decreased resistance. Thus, anangle formed by the magnetization directions of the pinned layer 3 andthe free layer 1 relatively changes according to the external magneticfield, and the electric resistance of the element in a directionperpendicular to a film plane changes according to the relative changein the angle. This change in the electric resistance can be read as achange in electric signal when current is passed between the electrodes5 and 6. As described above, in a CPP-GMR element, a current used forsensing is passed in a direction perpendicular to a film plane.

Conventionally, consideration has been given to the use of a materialsuch as Cu, Ag or the like for a nonmagnetic layer in a CPP-GMR element.However, metallic materials such as Cu, Ag and the like that have beenused conventionally have a specific resistance of 2 μΩ·cm or lower,which is too low as the resistance value of a material for thenonmagnetic layer of the element in which current is passedperpendicularly. Preferably, a material for the nonmagnetic layer of theelement in which current is passed in a direction perpendicular to afilm plane has a specific resistance of 4 μΩ·cm or higher.

Meanwhile, preferably, the material for the nonmagnetic layer has aspecific resistance reduced to some extent so that the element canprovide a high MR ratio. The specific resistance of the material ispreferably 200 μΩ·cm or lower and more preferably 100 μΩ·cm or lower.The specific resistances values of Co and Fe that are included in themagnetic layers are on the order of 5.6 μΩ·cm and 10.7 μΩ·cm,respectively. A material having a specific resistance up to about twiceas high as these values, namely 20 μΩ·cm or lower is used most suitablyas the material for the nonmagnetic layer.

As is apparent from the above-mentioned values, in this description, thespecific resistance of a metal used for a nonmagnetic layer is based ona bulk state. Generally, a metal film that is made thin so as to be usedin a magnetoresistive element has a specific resistance twice to severaltimes as high as that of a bulk form of the same metallic material. Thisspecific resistance value depends on conditions such as a film thicknessand the like. Hence, each specific resistance value described herein isbased on a bulk state so that an appropriate metallic material can bespecified clearly.

The film thickness of the nonmagnetic layer 2 falls within such a rangethat an exchange interaction between the free layer 1 and the pinnedlayer 3 through the nonmagnetic layer is preferably weakened, and mostpreferably decreased to substantially zero. Accordingly, the filmthickness of the nonmagnetic layer is preferably not less than 1.2 nmand most preferably not less than 2 nm. When a spin diffusion length ofelectrons is taken into consideration, the film thickness of thenonmagnetic layer is preferably not more than 20 nm and most preferablynot more than 10 nm so as not to lower the MR ratio.

As the film thickness of the nonmagnetic layer is increased, an exchangeinteraction between the magnetic layers may be attenuated whileoscillating between ferromagnetism (the magnetization directions becomeparallel to each other) and antiferromagnetism (the magnetizationdirections become anti-parallel to each other). As typically shown inFIG. 3, as a film thickness (T) of the nonmagnetic layer is increased,magnetic coupling force (H coupling) between the magnetic layers that isgenerated by the exchange interaction is attenuated gradually whileoscillating between ferromagnetic coupling and antiferromagneticcoupling. In this case, even when the film thickness of the nonmagneticlayer falls within, for example, the above range (1.2 to 20 nm), theexchange interaction between the magnetic layers may become too strong.Thus, the film thickness of the nonmagnetic layer should be determinedby a point at which an oscillating coupling curve crosses a horizontalaxis (H coupling=0) of FIG. 3 or a point in the vicinity thereof, ratherthan simply being determined so as to fall within the above-mentionedrange.

Specifically, the film thickness of the nonmagnetic layer is determinedso that the magnetic coupling force (H coupling) between the free layerand the pinned layer has an absolute value preferably not more than 20%(|H coupling|≦0.2×|−p|) and more preferably not more than 10% of that ofthe magnetic coupling force in the most antiferromagnetic state. Asshown in FIG. 3, this film thickness is determined so that a magneticcoupling force falls within a range between “−a” and “a”, where “a”indicates 20% of an absolute value of the maximum antiferromagneticcoupling force (0.2×|−p|=a). For the sake of convenience, in FIG. 3,ferromagnetism is indicated as a positive magnetic coupling force, andantiferromagnetism is indicated as a negative magnetic coupling force.

As for an artificial lattice film in practical use, consideration alsoshould be given to ferromagnetic coupling (orange peel coupling) causedby roughness in addition to the indirect exchange interaction. Thus,more preferably, the indirect exchange interaction is zero or isantiferromagnetic within a range satisfying the above-mentionedcondition.

Preferably, the nonmagnetic layer has an area of not more than 0.01 μm².The area of the nonmagnetic layer is defined as an area through which acurrent used for sensing (sense current) is passed. In a TMR element,when a film area is limited to this extent, the resistance value becomestoo high. The area of the nonmagnetic layer is more preferably not morethan 0.008 μm² and most preferably not more than 0.005 μm². Although alower limit of the area is not particularly limited thereto, preferably,the area of the nonmagnetic layer is not less than 0.0001 μm².

A metal constituting a main component of the nonmagnetic layer may be inthe form of a single metal or an alloy. The nonmagnetic layer maycontain at least one selected from the group consisting of Be, Bi, Cr,Hf, In, Ir, Mg, Mn, Mo, Nb, Os, Pd, Pt, Re, Ru, Rh, Sb, Se, Ta, Th, Ti,Tl, V, W, Y and Zr. Further, an alloy of metals selected from theabove-mentioned group or an alloy of metals of a metal selected from theabove-mentioned group and a metal other than the metals in the group maybe used.

Most preferably, Cr is used as a metallic material for the nonmagneticlayer. The specific resistance of Cr is as high as 12.8 μΩ·cm, and aFe/Cr multi-layer film provides a substantial amount of change inmagnetic resistance. Thus, when the nonmagnetic layer contains Cr as amain component, preferably, the magnetic layer contains Fe. When usingthe nonmagnetic layer containing Cr as a main component, morepreferably, at least one selected from the free layer and the pinnedlayer is composed of one or more magnetic films, and at least themagnetic film adjacent to the nonmagnetic layer contains Fe as a maincomponent.

In the element shown in FIG. 1, the magnetic layers of a two-layeredstructure are used. When a multi-layered magnetic layer is used, apreferred combination with a material for a nonmagnetic layer can berealized while other properties such as soft magnetization of themagnetic layer also can be taken into consideration.

When the nonmagnetic layer 2 contains Cr as a main component, in thefree layer 1, a Fe film should be used as an interface magnetic layer102, and a film of a softer magnetic material than Fe such as a Ni—Fefilm and a Ni—Fe—Co film should be used as a magnetic layer 101.Further, also in the pinned layer 3, a Fe film may be used as aninterface magnetic layer 301, and a magnetic film of Co, Co—Fe, Ni—Fe,Ni—Fe—Co or the like may be used as a magnetic layer 302 so that amagnetization rotation suppressing effect exerted by the magnetizationrotation suppressing layer 4 can be reinforced.

Other preferred examples of the metallic material for the nonmagneticlayer include Ir, Ru and Rh. When the nonmagnetic layer contains atleast one selected from Ir, Ru and Rh as a main component, preferably,the magnetic layer contains Fe, Co and Ni or an alloy of these metals.When using the nonmagnetic layer containing at least one selected fromIr, Ru and Rh as a main component, more preferably, at least oneselected from the free layer and the pinned layer is composed of one ormore magnetic films, and at least the magnetic film adjacent to thenonmagnetic layer contains at least one selected from Fe, Co and Ni as amain component.

The pinned layer 3 may be formed of a so-called synthetic ferrimagneticpinned layer in which a pair of ferromagnetic layers are coupledantiferromagnetically through a nonmagnetic layer. This configurationallows an effect of pinning down the magnetization of the pinned layerto be enhanced. Further, part of the magnetization of the pinned layeris cancelled, so that a magnetic flux leaking from the pinned layer tothe free layer is reduced, thereby allowing a leakage magnetic field tobe adjusted. In this case, each of the ferromagnetic layers suitably hasa thickness of 1 to 3 nm. The nonmagnetic layer to be interposed betweenthe ferromagnetic layers is made suitably of a material such as Ru, Iror the like. The film thickness of the nonmagnetic layer should be 0.3to 1.2 nm.

The magnetization rotation suppressing layer 4 can be made of a materialsuch as PtMn, NiMn, PdPtMn, CrMn, FeMn or the like. There is no limit toa material for the electrodes 5 and 6, and a material such as Cu or thelike that has been used conventionally can be used.

Although not shown in FIG. 1, a substrate on which the respective thinfilms described above are formed should be formed of a substrate ofglass, MgO, Si, Al₂O₃—TiC or the like with a smooth surface. For thefabrication of an MR head, an Al₂O₃—TiC substrate is used suitably.

As required by an application, a magnetic shield or the like further maybe formed between the substrate and the above-mentioned thin films.Further, a base layer may be interposed between the substrate and themagnetization rotation suppressing layer for the purposes of improving aproperty of the magnetization rotation suppressing layer and the like.As the base layer, a Ta film, a NiFe film, a NiFeCr alloy film, alaminate of these films or the like can be used. The thickness of thebase layer is suitably on the order of 1 to 10 nm.

The multi-layered film shown in FIG. 1 may be formed by laminating therespective films in a reverse order starting from an upper side of thefigure (from a side of the free layer 1) instead of laminating in anorder starting from a lower side of the figure. Although notparticularly limited thereto, sputtering is used suitably as a method offorming the respective layers. The sputtering may be any one of DCsputtering, RF sputtering, iron beam sputtering and the like.

The present invention is also applicable to an element having aconfiguration using pinned layers and a free layer interposed betweenthe pinned layers. As shown in FIG. 2, this element can be formed by,for example, laminating a lower electrode 5, a magnetization rotationsuppressing layer 4, a pinned layer 3, a nonmagnetic layer 2, a freelayer 1, a nonmagnetic layer 2, a pinned layer 3, a magnetizationrotation suppressing layer 4, and an upper electrode 6 in this order.Similarly, in this case, an interface magnetic layer 102 (301) may beprovided in the free layer 1 (pinned layer 3) adjacent to thenonmagnetic layer 2.

FIG. 4 shows an example of an MR head using the above-describedmagnetoresistive element according to the present invention.

An MR element 100 is interposed between an upper magnetic shield (commonshield) 13 and a lower magnetic shield 16. These magnetic shields areprovided so that an external magnetic field from other than a mediumexerts no influence on the element. As a material for the shields, asoft magnetic film of an alloy of Ni—Fe, Fe—Al—Si, Co—Nb—Zr or the likeis used suitably. In this head, the magnetic shields 13 and 16 alsofunction as electrodes for feeding current to the element. In a portionbetween both the electrodes other than an MR element portion, aninsulation film 18 is provided. As shown in the figure, conductivespacers 20 may be interposed between the MR element and the shields. Inthis head, the MR element 100 and the conductive spacers 20 constitute areproduction gap 17.

A nonmagnetic layer 14 and an upper core 12 further are laminated inorder on the common shield 13. These members together with coils 11constitute a recording head.

As shown in FIG. 5, in a magnetic head using a CIP-GMR element,insulation films 18 are interposed as shield gap materials between an MRelement 200 and magnetic shields 13 and 16. In this MR element, a sensecurrent flowing between electrodes 19 flows in a film plane direction,and thus it is required that the element be insulated electrically fromthe shield members using the insulation films 18.

In the MR head shown in FIG. 4, the conductive spacer 20 is not anindispensable member. Therefore, when the reproduction gap 17 isrequired to be narrowed, the spacer can be made thinner or removed. Onthe other hand, in the MR head shown in FIG. 5, it is required that theinsulation film 18 have a thickness not less than a given thickness sothat electrical insulation can be secured. Accordingly, there is a limitto the degree to which a reproduction gap 17 can be narrowed. Thus, theMR head according to the present invention has the advantage that amagnetic gap can be narrowed further.

As shown in FIGS. 6 and 7, a hard disk device 110 using this MR headincludes a slider 120 for supporting the MR head, a head supportingdevice 130 for supporting the slider, an actuator 114 for allowing theMR head to perform a tracking operation through the head supportingdevice, and a disk-driving motor 112 for driving a disk 116 to rotate.The head supporting device 130 includes an arm 122 and a suspension 124.

The disk-driving motor 112 drives the disk 116 to rotate at apredetermined speed. The actuator 114 allows the slider 120 supportingthe MR head to move in a radial direction of the disk 116 so that the MRhead can be given access to a predetermined data track on the disk 116.The actuator 114 is formed of, for example, a linear or rotary typevoice coil motor.

The slider 120 for supporting the MR head is formed of, for example, anair-bearing slider. In this case, the slider 120 is brought into contactwith a surface of the disk 116 in starting and stopping operations ofthe hard disk device 110. In recording and reproducing operations of thehard disk device 110, the slider 120 is maintained over the surface ofthe disk 116 by an air bearing formed between the disk 116 being rotatedand the slider 120. The MR head supported by the slider 120 performsinformation recording and reproduction with respect to the disk 116.

EXAMPLE (Example 1)

A magnetoresistive element having a configuration shown in FIG. 8 wasfabricated by using a multi-sputtering device. As a material for asubstrate 7, Si was used. A Cu film, a Pt—Mn film and a Co—Fe film wereformed as a lower electrode 5 (used also as a base layer), amagnetization rotation suppressing layer 4, and a pinned magnetic layer302, respectively. Further, Fe films were formed as interface magneticlayers 301 and 102. Furthermore, a Cr film, a Ni—Fe film and a Cu filmwere formed as a nonmagnetic layer 2, a soft magnetic layer 101 and anupper electrode 6, respectively. By using a vacuum chamber exhausted toa pressure of not more than 1×10⁻⁸ Torr, sputtering was performed whilefeeding an Ar gas so that a pressure of about 0.8 m Torr was attained.

The film configuration of the element thus fabricated is shown belowalong with the thicknesses of the respective films (hereinafter, filmthicknesses are expressed in nm).

-   -   Element A: Substrate/Cu (500)/Pt_(0.5)Mn_(0.5)        (30)/Co_(0.9)Fe_(0.1) (2)/Fe (2)/Cr (2)/Fe (1)/NiFe (10)/Cu

It has been known that as shown in FIG. 3, magnetic coupling generatedby an exchange interaction in the case of using a Cr film as a materialfor a nonmagnetic layer is attenuated while oscillating betweenferromagnetic coupling and antiferromagnetic coupling. When the Cr filmhas a thickness of 2 nm, the magnetic coupling becomes approximatelyzero.

For comparison, an element in which Cu was used as a material for anonmagnetic layer was fabricated by the same method as that used in theabove-mentioned case. However, in this case, since the MR ratio wassubstantially lowered by the insertion of Fe interface layers, insteadof inserting the interface magnetic layers, a pinned layer and a freelayer each having an increased thickness were used. The filmconfiguration of this element is shown below.

-   -   Element B: Substrate/Cu (500)/Pt_(0.5)Mn_(0.5)        (30)/Co_(0.9)Fe_(0.1) (3)/Cu (2)/NiFe (11)/Cu

Each of the MR elements thus obtained was taken out of a film-formingdevice and subjected to a heat treatment in which the MR element waskept for 5 hours at a temperature of 250° C. under a magnetic field of 5kOe in a vacuum of 1×10⁻⁵ Torr or less. Then, with respect to each ofthe elements, patterning was performed using an electron-beam exposuremachine so that an element portion of 0.1×0.1 μm² was obtained. Further,each element was processed so that electrodes could be taken out. Afterthat, MR properties of the elements were evaluated by a DC four-terminalmethod. In the evaluation, a magnetic field of up to 400 kA/m at roomtemperature was applied and a current of the same magnitude was fed toeach of the elements. The results of the evaluation are shown in thefollowing table. The amount of change in resistance is expressed as avalue relative to that of Sample B.

TABLE 1 Element MR ratio (%) Change in Resistance A 55 10 B 48  1

Compared with Element B that is a conventional MR element, Element Aexhibits no substantial difference in the MR ratio while having a largedifference in the amount of change in resistance that is a factordirectly affecting the output.

Next, each of the Elements A and B was used to constitute the MR headshown in FIG. 4, and properties of the MR heads thus obtained wereevaluated. A Al₂O₃—TiC substrate was used as a substrate, and aNi_(0.8)Fe_(0.2) alloy and Al₂O₃ were used as materials for magneticshields and an insulation film, respectively.

With respect to each of these heads, an evaluation of the output wasperformed by applying an alternating signal magnetic field of about 3kA/m while feeding a direct current as a sense current betweenelectrodes (magnetic shields). The results of the evaluations are shownin the following table. The output shown in the table also is expressedas a value relative to that of the MR head using the Element B.

TABLE 2 Element Relative Output A +6 B 0

The MR head using the Element A provided a larger output than that ofthe MR head using the conventional Element B.

(Example 2)

In the same manner as in Example 1, an MR element having a structureshown in FIG. 9 was fabricated. However, in this case, although shown tobe a single layer, a pinned layer 3 was formed of a syntheticferrimagnetic pinned layer of CoFe/Ru/CoFe. A glass substrate was usedas a substrate 7, and Cu films were used as a lower electrode 5 and anupper electrode 6. Further, a Ni—Mn alloy film, a Ru film, aCo_(0.9)Fe_(0.1) alloy film were used as a magnetization rotationsuppressing layer 4, a nonmagnetic layer 2, and a free layer 1,respectively. No interface magnetic layer was formed in this case. Thefilm configuration of this element is shown below.

-   -   Element C: Substrate/Cu (500)/Ta (3)/Ni_(0.5)Mn_(0.5)        (30)/Co_(0.9)Fe_(0.1) (2)/Ru (0.7)/Co_(0.9)Fe_(0.1) (3)/Ru        (2.5)/Co_(0.9)Fe_(0.1) (2)/Ru (2.5)/Co_(0.9)Fe_(0.1) (3)/Ru        (0.7)/Co_(0.9)Fe_(0.1) (2)/Ni_(0.5)Mn_(0.5) (30)/Cu

In this configuration, a Ta film functions as a base film for improvinga property of the magnetization rotation suppressing layer. In the samemanner, the following configurations also were obtained by formingnonmagnetic films of Ir and Rh, respectively.

-   -   Element D: Substrate/Cu (500)/Ta (3)/Ni_(0.5)Mn_(0.5)        (30)/Co_(0.9)Fe_(0.1) (2)/Ru (0.7)/Co_(0.9)Fe_(0.1) (3)/Ir        (2.5)/Co_(0.9)Fe_(0.1) (2)/Ir (2.5)/Co_(0.9)Fe_(0.1) (3)/Ru        (0.7)/Co_(0.9)Fe_(0.1) (2)/Ni_(0.5)Mn_(0.5) (30)/Cu    -   Element E: Substrate/Cu (500)/Ta (3)/Ni_(0.5)Mn_(0.5)        (30)/Co_(0.9)Fe_(0.1) (2)/Ru (40.7)/Co_(0.9)Fe_(0.1) (3)/Rh        (2.5)/Co_(0.9)Fe_(0.1) (2)/Rh (2.5)/Co_(0.9)Fe_(0.1) (3)Ru        (0.7)/Co_(0.9)Fe_(0.1) (2)/Ni_(0.5)Mn_(0.5) (30)/Cu

As in the case of using a Cr film as the nonmagnetic layer, magneticcoupling generated by an exchange interaction in the case of using afilm of Ru, Rh or Ir as the nonmagnetic layer is attenuated whileoscillating between ferromagnetic coupling and antiferromagneticcoupling as the thickness of the nonmagnetic layer is increased. Whenthe thickness of the above-mentioned film of Ru or the like is 2.5 nm,as in the case of using the Cr film (Example 1), the magnetic couplingsatisfies the relationship |H coupling|≦0.2×|p| because the exchangeinteraction is attenuated to a sufficient degree.

For comparison, in the same manner, the following configuration also wasobtained by forming a nonmagnetic film of Cu.

-   -   Element F: Substrate/Cu (500)/Ni_(0.5)Mn_(0.5)        (30)/Co_(0.9)Fe_(0.1) (2)/Ru (0.7)/Co_(0.9)Fe_(0.1) (3)/Cu        (2.5)/Co_(0.9)Fe_(0.1) (2)/Cu (2.5)/Co_(0.9)Fe_(0.1) (3)/Ru        (0.7)/Co_(0.9)Fe_(0.1) (2)/Ni_(0.5)Mn_(0.5) (30)/Cu

With respect to each of the MR elements thus fabricated, a heattreatment followed by patterning was performed, and then measurementswere made of MR effects by feeding current in a direction perpendicularto a film plane by the same method as that used in Example 1. Theresults of the measurements are shown in Table 3. In the table, theamounts of change in resistance are expressed as values relative to thatof Element F.

TABLE 3 Element MR ratio (%) Change in Resistance C 41 4 D 55 7 E 39 5 F58 1

As can be seen from Table 3, it was confirmed that each of Elements D toE could provide a larger amount of change in resistance than that of theElement F that was a conventional MR element, thereby allowing a largeoutput to be obtained.

The MR element according to the present invention can secure a largeoutput while allowing adaptation to a narrowed gap. Thus, amagnetoresistive head and a magnetic information recording andreproducing device using this MR element can be adapted to high-densityrecording.

1. A magnetoresistive element comprising: a first magnetic layer; anonmagnetic layer; a second magnetic layer laminated to the firstmagnetic layer through the nonmagnetic layer; and a magnetizationrotation suppressing layer for suppressing magnetization rotation of thesecond magnetic layer, wherein magnetization of the first magnetic layeris rotated more easily by an external magnetic field than magnetizationof the second magnetic layer; a current used for sensing is passes in adirection perpendicular to a film plane and parallel to a stackingdirection of the first magnetic layer, the non-magnetic layer and thesecond magnetic layer; the nonmagnetic layer is formed of a thin filmwhose main component is a metal having a specific resistance of 4 μΩ·cmto 200 μΩ·cm; and a film thickness of the nonmagnetic layer isdetermined so that magnetic coupling force between the first magneticlayer and the second magnetic layer has an absolute value not more than20% of that of the magnetic coupling force in the most antiferromagneticstate, the magnetic coupling force being attenuated while oscillatingbetween ferromagnetic coupling and antiferromagnetic coupling as thefilm thickness is increased.
 2. A magnetoresistive element comprising: afirst magnetic layer; a nonmagnetic layer; a second magnetic layerlaminated to the first magnetic layer through the nonmagnetic layer; anda magnetization rotation suppressing layer for suppressing magnetizationrotation of the second magnetic layer, wherein magnetization of thefirst magnetic layer is rotated more easily by an external magneticfield than magnetization of the second magnetic layer; a current usedfor sensing is passes in a direction perpendicular to a film plane andparallel to a stacking direction of the first magnetic layer, thenon-magnetic layer and the second magnetic layer; the nonmagnetic layeris formed of a thin film whose main component is a metal having aspecific resistance of 4 μΩ·cm to 200 μΩ·cm; and the nonmagnetic layeris formed of a thin film whose main component is a metal having aspecific resistance of 4 μΩ·cm to 200 μΩ·cm; and has an area of not morethan 0.01 μm².
 3. The magnetoresistive element according to claim 2,wherein the nonmagnetic layer contains at least one selected from thegroup consisting of Be, Bi, Cr, Hf, In, Ir, Mg, Mn, Mo, Nb, Os, Pd, Pt,Re, Ru, Rh, Sb, Se, Ta, Th, Ti, Tl, V, W, Y and Zr.
 4. Themagnetoresistive element according to claim 2, wherein the nonmagneticlayer has a film thickness of not less than 1.2 nm.
 5. Themagnetoresistive element according to claim 4, wherein the nonmagneticlayer has a film thickness of not more than 20 nm.
 6. Themagnetoresistive element according to claim 2, wherein the nonmagneticlayer contains Cr as a main component.
 7. The magnetoresistive elementaccording to claim 6, wherein at least one selected from the firstmagnetic layer and the second magnetic layer is composed of one or moremagnetic films, and at least the magnetic film adjacent to thenonmagnetic layer contains Fe as a main component.
 8. Themagnetoresistive element according to claim 2, wherein the nonmagneticlayer contains at least one selected from Ir, Ru and Rh as a maincomponent.
 9. The magnetoresistive element according to claim 8, whereinat least one selected from the first magnetic layer and the secondmagnetic layer is composed of one or more magnetic films, and at leastthe magnetic film adjacent to the nonmagnetic layer contains at leastone selected from Fe, Co and Ni as a main component.
 10. Amagnetoresistive head comprising a magnetoresistive element as claimedin claim 2 and a magnetic shield.
 11. A magnetic recording andreproducing device comprising a magnetoresistive head as claimed inclaim 10 and a magnetic recording medium used for performing informationrecording or reproduction using the magnetoresistive head.